Apparatus and methods for transferring ultrasonic energy to a bodily tissue

ABSTRACT

An apparatus includes a monolithically-constructed transmission member that defines a lumen along a longitudinal axis. The transmission member includes a first portion, a second portion, and a third portion. The first portion is configured to be coupled to an ultrasonic energy source. The second portion is configured to contact a bodily tissue to transfer ultrasonic energy from a first portion into the bodily tissue. The third portion is disposed between the first portion and the second portion and defines a cross-sectional moment of inertia that is less than at least one of a cross-sectional area moment of inertia of the first portion or a cross-sectional moment of inertia of the second portion.

This application is a continuation of U.S. patent application Ser. No.13/652,881, now U.S. Pat. No. 9,173,667, entitled “Apparatus and Methodfor Transferring Ultrasonic Energy to a Bodily Tissue,” filed Oct. 16,2012, which is incorporated herein by reference in its entirety.

BACKGROUND

The embodiments described herein relate generally to a device used inconjunction with an ultrasonic ablation device and, more specifically,to a transmission member configured to transfer ultrasonic energy to abodily tissue from an ultrasonic energy source.

Known ultrasonic energy transmission systems are used in many differentmedical applications, such as, for example, for medical imaging, todisrupt obstructions and/or ablate bodily tissue. In known ultrasonicenergy transmission systems for tissue ablation, ultrasonic energy istransferred from an ultrasonic energy source through a transducer hornand then a transmission member, such as a wire, to a distal head.Ultrasonic energy propagates through the transmission member as aperiodic wave thereby causing the distal head to vibrate. Suchvibrational energy can be used to ablate or otherwise disrupt bodilytissue, for example, a vascular obstruction, a kidney stone or the like.To effectively reach various sites for treatment of intravascularocclusions or regions within the urinary tract, such ultrasonictransmission members often have lengths of about 65 cm or longer.

Known ultrasonic transmission members are constructed to be flexibleenough to be passed through various bodily lumens, but also withsufficient strength to transmit ultrasonic energy to the distal tip(e.g., to ablate vascular or urinary obstructions). A stronger, moredurable transmission member allows for greater transmission of energybut may not be flexible or thin enough to be advanced through thevasculature to a desired treatment area. A thinner transmission membercan be more flexible but is less durable and more susceptible tobreakage.

In an attempt to find a balance between strength and flexibility, someknown ultrasonic transmission members are tapered along a longitudinalaxis of the transmission member such that the diameter of the distal endportion decreases to allow greater flexibility. For example, some knowntransmission members can include a diameter at the proximal end that isgreater than a diameter at a distal end. Moreover, some knowntransmission members can include a distal tip or “head” that is weldedto the reduced diameter section, and which is positioned adjacent thetissue to be treated. Such transmission members can be prone to breakageat or near the distal end of the transmission member where thecross-sectional area of the transmission member becomes smaller and/orat the discontinuous region where the two pieces are joined. Similarlystated, such breakage is generally caused by stress concentration due totransverse vibrations and fatigue. Thus, one difficulty related totransmission of ultrasonic energy through a relatively long transmissionmember of known design is premature wear and breakage of thetransmission member.

Furthermore, the coupling of the distal head to the distal end of thetransmission member results in a discontinuity between the transmissionmember and the distal head due to, for example, weld material, adhesivematerial, or the like. Such discontinuities can produce reflections ofthe ultrasonic wave and result in losses of ultrasonic energy. Toovercome the energy losses and inefficiency in energy transfer due toreflections or the like, some known systems increase the level ofultrasonic energy transferred through the transmission member. Similarlystated, some known systems apply a high level of energy at the proximalend portion to overcome the inefficiencies of the transmission member(e.g., at the distal end). However, the increase in the ultrasoundenergy transferred through the transmission member can increase stresson the transmission member and, consequently, can result in prematurefatigue and breakage. In addition to the loss of transmissionefficiency, known transmission members constructed of multiple piecesare expensive and can be complicated to manufacture.

Thus, a need exists for an improved apparatus and methods fortransferring ultrasonic energy from an ultrasonic energy source to abodily tissue.

SUMMARY

Devices and methods of use of a transmission device for use with anultrasonic ablation system are described herein. In some embodiments, anapparatus includes a monolithically constructed transmission member thatdefines a lumen along a longitudinal axis. The transmission memberincludes a first portion, a second portion, and a third portion. Thefirst portion can be coupled to an ultrasonic energy source. The secondportion is configured to be disposed within the body to transferultrasonic energy from the first portion into the bodily tissue. Thethird portion is disposed between the first portion and the secondportion and defines a cross-sectional moment of inertia that is lessthan at least one of a cross-sectional area moment of inertia of thefirst portion or a cross-sectional moment of inertia of the secondportion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a system for delivering ultrasonic energyto a bodily tissue according to an embodiment.

FIG. 2 is a cross-sectional view of an ultrasonic transducer included inthe system of FIG. 1.

FIG. 3 is a schematic illustration of a transmission member, accordingto an embodiment.

FIG. 4 is an illustration of a transmission member, according to anembodiment.

FIG. 5 is a cross-sectional view of the transmission member of FIG. 4taken along the line X₁-X₁.

FIG. 6 is a cross-sectional view of the transmission member of FIG. 4taken along the line X₂-X₂.

FIG. 7 is an illustration of a probe assembly according to anembodiment.

FIG. 8 is a cross-sectional view of the probe assembly of FIG. 7 takenalong the like X₃-X₃.

FIG. 9 is a schematic illustration of a probe assembly according to anembodiment.

FIG. 10 is a schematic illustration of a probe assembly according to anembodiment.

FIG. 11 is a flowchart illustrating a method for transferring ultrasonicenergy to a bodily tissue.

FIG. 12 is an enlarged view of a portion of a probe assembly accordingto an embodiment coupled to a transducer horn.

DETAILED DESCRIPTION

Devices and methods of use of a transmission device for use with anultrasonic ablation system are described herein. In some embodiments, anapparatus includes a monolithically constructed transmission member thatdefines a lumen along a longitudinal axis. The transmission memberincludes a first portion, a second portion, and a third portion. Thefirst portion can be coupled to an ultrasonic energy source. The secondportion is configured to be disposed within the body (e.g., adjacent toor in contact with a bodily tissue) to transfer ultrasonic energy from afirst portion into the bodily tissue. The third portion is disposedbetween the first portion and the second portion and defines across-sectional moment of inertia that is less than at least one of across-sectional area moment of inertia of the first portion or across-sectional moment of inertia of the second portion.

In some embodiments, an apparatus includes a transmission member and anouter member coupled thereto. The transmission member includes a firstend portion and a second end portion, and defines a lumen therethrough.The transmission member is configured to transfer ultrasonic energy froma first end portion to a second end portion. The transmission memberfurther includes a sidewall that defines an elongated openingtherethrough that is in fluid communication with the lumen. At least aportion of the outer member is disposed about the elongated opening ofthe transmission member such that the lumen is substantially fluidicallyisolated from a region outside of the outer member. In some embodiments,the outer member is fixedly coupled to the transmission member, forexample, by a weld, an adhesive or the like. In some embodiments, thetransmission member is monolithically constructed.

In some embodiments, a kit includes an ultrasonic transducer assemblyand multiple transmission members each configured to be coupled to theultrasonic transducer assembly. Each transmission member from themultiple transmission members has a diameter substantially the same asthe diameter of each of the other transmission members. A firsttransmission member included in the multiple transmission membersdefines a flexural stiffness that is different than a flexural stiffnessof a second transmission member included in the multiple transmissionmembers. In some embodiments, for example, the first transmission membercan define a cross-sectional area moment of inertia that is differentthan a cross-sectional area moment of inertia defined by the secondtransmission member.

In some embodiments, a method includes inserting at least a distal endportion of a monolithically constructed transmission member into abodily lumen. The transmission member includes a proximal end portionand a flexible portion. The proximal end portion is coupled to anultrasonic energy source. The flexible portion is disposed between theproximal end portion and the distal end portion and defines across-sectional area moment of inertia that is less than at least one ofa cross-sectional area moment of inertia of the proximal end portion ora cross-sectional area moment of inertia of the distal end portion. Themethod further includes transmitting ultrasonic energy from the proximalend portion towards the distal end portion such that a portion of theultrasonic energy is delivered to a target tissue within the bodilylumen. In some embodiments, the flexible portion can define across-sectional area moment of inertia that is different than across-sectional area moment of inertia defined by the proximal endportion and/or the distal end portion.

As used in this specification, the terms “proximal” and “distal” referto the direction closer to and away from, respectively, a user who wouldplace the device into contact with a patient. Thus, for example, the endof a device first touching the body of the patient would be the distalend, while the opposite end of the device (e.g., the end of the devicebeing manipulated by the user) would be the proximal end of the device.

As used herein, the terms “about” and “approximately” generally meanplus or minus 10% of the value stated. For example, about 0.5 wouldinclude 0.45 and 0.55, about 10 would include 9 to 11, about 1000 wouldinclude 900 to 1100.

As used herein, the term “set” can refer to multiple features or asingular feature with multiple parts. For example, when referring to setof walls, the set of walls can be considered as one wall with multipleportions, or the set of walls can be considered as multiple, distinctwalls. Thus, a monolithically-constructed item can include a set ofwalls. Such a set of walls can include, for example, multiple portionsthat are either continuous or discontinuous from each other. A set ofwalls can also be fabricated from multiple items that are producedseparately and are later joined together (e.g., via a weld, an adhesive,or any suitable method).

As used herein, the term “target tissue” refers to an internal orexternal tissue of or within a patient to which ultrasonic energyablation techniques are applied. For example, a target tissue can becancer cells, tumor cells, lesions, vascular occlusions, thrombosis,calculi, uterine fibroids, bone metastases, adenomyosis, or any otherbodily tissue. Furthermore, the presented examples, of target tissuesare not an exhaustive list of suitable target tissues. Thus, theultrasonic energy systems described herein are not limited to thetreatment of the aforementioned tissues and can be used on any suitablebodily tissue. Moreover, a “target tissue” can also include anartificial substance within or associated with a body, such as forexample, a stent, a portion of an artificial tube, a fastener within thebody or the like. Thus, for example, the ultrasonic energy systemsdescribed herein can be used on or within a stent or artificial bypassgraft.

As used herein, the term “stiffness” relates to an object's resistanceto deflection, deformation, and/or displacement produced by an appliedforce, and is generally understood to be the opposite of the object's“flexibility.” For example, a wall of a tube with greater stiffness ismore resistant to deflection, deformation and/or displacement whenexposed to a force than a wall of a tube having a lower stiffness.Similarly stated, a tube having a higher stiffness can be characterizedas being more rigid than a tube having a lower stiffness. Stiffness canbe characterized in terms of the amount of force applied to the objectand the resulting distance through which a first portion of the objectdeflects, deforms, and/or displaces with respect to a second portion ofthe object. When characterizing the stiffness of an object, thedeflected distance may be measured as the deflection of a portion of theobject different than the portion of the object to which the force isdirectly applied. Said another way, in some objects, the point ofdeflection is distinct from the point where force is applied.

Stiffness (and therefore, flexibility) is an extensive property of theobject being described, and thus is dependent upon the material fromwhich the object is formed as well as certain physical characteristicsof the object (e.g., cross-sectional shape, length, boundary conditions,etc.). For example, the stiffness of an object can be increased ordecreased by selectively including in the object a material having adesired modulus of elasticity, flexural modulus and/or hardness. Themodulus of elasticity is an intensive property of (i.e., is intrinsicto) the constituent material and describes an object's tendency toelastically (i.e., non-permanently) deform in response to an appliedforce. A material having a high modulus of elasticity will not deflectas much as a material having a low modulus of elasticity in the presenceof an equally applied stress. Thus, the stiffness of the object can bedecreased, for example, by introducing into the object and/orconstructing the object of a material having a relatively low modulus ofelasticity.

The stiffness of an object can also be increased or decreased bychanging a physical characteristic of the object, such as the shape orcross-sectional area of the object. For example, an object having alength and a cross-sectional area may have a greater stiffness than anobject having an identical length but a smaller cross-sectional area. Asanother example, the stiffness of an object can be reduced by includingone or more stress concentration risers (or discontinuous boundaries)that cause deformation to occur under a lower stress and/or at aparticular location of the object. Thus, the stiffness of the object canbe decreased by decreasing and/or changing the shape of the object.

The stiffness (or inversely, the flexibility) of an elongated object,such as a catheter or tube can be characterized by its flexuralstiffness. The flexural stiffness of an object can be used tocharacterize the ease with which the object deflects under a given force(e.g., the ease with which the object deflects when the object is movedalong a tortuous path within the body). The flexural stiffness of anobject, such as a catheter, transmission member or the like, can bemathematically expressed as shown below:

$k = \frac{3\;{EI}}{L^{3}}$

where k is the flexural stiffness of the object, E is the modulus ofelasticity of the material from which the object is constructed, I isthe area moment of inertia of the object (defined below), and L is thelength of the object.

As used herein, the terms “cross-sectional area moment of inertia,”“area moment of inertia,” and/or “second moment of area” relate to anobject's resistance to deflection or displacement around an axis thatlies in a cross-sectional plane. The area moment of inertia is dependenton the cross-sectional area and/or shape of the object and can bemathematically expressed as a function of a cross-section of the object.The area moment of inertia of an object (e.g., such as the tubesdisclosed herein) is described having units of length to the fourthpower (e.g., in⁴, mm⁴, cm⁴, etc.). In this manner, the “area moment ofinertia” is differentiated from the “moment of inertia” or “mass momentof inertia” which is expressed having units of mass times units oflength to the second power (e.g., kg*m², lb_(m)*ft², etc.).

Two mathematical formulas are used herein to define an area moment ofinertia for a substantially annular cross-sectional shape and for asubstantially arc-shaped cross-sectional shape. The area moment ofinertia for the annular cross-section shape is expressed below as:

$I = \frac{\pi( {d_{o}^{4} - d_{i}^{4}} )}{64}$

where d_(o) is an outside diameter of the annulus and d_(i) is an innerdiameter of the annulus.

The area moment of inertia for an arced cross-sectional shape isexpressed below as:

$I = {\frac{r^{3}t}{2}\lbrack {\alpha + {\cos( {\alpha - \frac{\pi}{2}} )}} \rbrack}$

where r is the radius of the arc, t is the thickness of the arc segment(e.g., d_(o)−d_(i)), and α is the subtended angle of the radius. Forcontinuity with the area moment of inertia equation for the annularcross-section, the equation can be expressed as shown below:

$I = {\frac{d_{i}^{3}( {d_{o} - d_{i}} )}{16}\lbrack {\alpha + {\cos( {\alpha - \frac{\pi}{2}} )}} \rbrack}$

Embodiments described herein relate to ultrasonic energy ablationsystems. In such systems a transmission member can be operably coupledto an ultrasonic energy source to deliver ultrasonic energy to a targetbodily tissue. For example, FIG. 1 is an illustration of an ultrasonicenergy ablation system 100, according to an embodiment. The ultrasonicenergy ablation system 100 (also referred to herein as “ultrasonicsystem” or simply “system”) includes an ultrasonic generator 180, a footswitch 170, an ultrasonic transducer assembly 150, and a probe assembly110. The ultrasonic generator 180 (or “generator”) can be any suitablegenerator configured to generate, control, amplify, and/or transfer anelectric signal (e.g., a voltage) to the transducer assembly 150.

The ultrasonic generator 180 includes at least a processor, a memory andthe circuitry (not shown in FIG. 1) to produce an electronic signal(i.e., a current and a voltage) having the desired characteristics thatcan be received by the ultrasonic transducer assembly 150 and convertedinto ultrasonic energy. In some embodiments, the ultrasonic generator180 can be electrically coupled to (e.g., “plugged into”) an electricreceptacle such that the ultrasonic generator 180 receives a flow ofelectric current. For example, in some embodiments, the ultrasonicgenerator 180 can be plugged into a wall outlet that deliversalternating current (AC) electrical power at a given voltage (e.g.,120V, 230V, or other suitable voltage) and a given frequency (e.g., 60Hz, 50 Hz, or other suitable frequency).

Although not shown in FIG. 1, the ultrasonic generator 180 includes theelectronic circuitry, hardware, firmware and or instructions to causethe ultrasonic generator 180 to act as a frequency inverter and/orvoltage booster. In this manner, the ultrasonic generator 180 canproduce and/or output a voltage to the transducer assembly 150 havingthe desired characteristics to produce the desired ultrasonic energyoutput. For example, in some embodiments, the ultrasonic generator 180can receive AC electrical power at a frequency of approximately 60 Hzand a voltage of approximately 120V and convert the voltage to afrequency up to approximately 20,000 Hz to 35,000 Hz with a voltage ofapproximately 500-1500 VAC (RMS). Thus, the ultrasonic generator 180 cansupply the transducer assembly 150 with a flow of AC electrical powerhaving an ultrasonic frequency.

As shown in FIG. 1, the system 100 includes the foot switch 170 that isin electric communication with the ultrasonic generator 180 via a footswitch cable 171. The foot switch 170 includes a set of pedals 172(e.g., two pedals as shown) that are operative in controlling thedelivery of the ultrasonic electrical energy supplied to the ultrasonictransducer assembly 150. For example, in some embodiments, a user (e.g.,a physician, technician, etc.) can engage and/or depress one or more ofthe pedals 172 to control the current supplied to the ultrasonictransducer assembly 150 such that, in turn, the probe assembly 110delivers the desired ultrasonic energy to the bodily tissue, as furtherdescribed in detail herein.

The transducer assembly 150 is in electric communication with theultrasonic generator 180 via a transducer cable 167. In this manner, thetransducer assembly 150 can receive an electrical signal (i.e., voltageand current) from the ultrasonic generator 180. The transducer assembly150 is configured to produce and amplify the desired ultrasonic energyvia a set of piezoelectric members 162 (i.e., piezoelectric rings) andan ultrasonic horn 163 (see e.g., FIG. 2), and transfer the ultrasonicenergy to the probe assembly 110 and/or the transmission member 120. Thetransducer assembly 150 can be any suitable assembly of the types shownand described herein.

For example, in some embodiments, as shown in FIG. 2, the transducerassembly 150 includes a housing 151 having a proximal end portion 152and a distal end portion 153. The housing 151 is configured to house orotherwise enclose at least a portion of a flow tube 157, a bolt 158, aback plate 160, a set of insulators 161, a set of piezoelectric rings162, and a transducer horn 163.

The proximal end portion 152 of the housing 151 is coupled to a proximalcover 154 (e.g., via an adhesive, a press or friction fit, a threadedcoupling, a mechanical fastener, or the like). The proximal cover 154defines an opening 155 such that the proximal cover 154 can receive aportion of a connector 156 (e.g., a luer connector) on a proximal sidethereof (e.g., substantially outside the housing 151) and a portion ofthe flow tube 157 on a distal side thereof (e.g., substantially insidethe housing 151). Expanding further, the proximal cover 154 can receivethe connector 156 and the flow tube 157 such that the proximal cover 154forms a substantially fluid tight seal with the connector 156 and theflow tube 157. In this manner, a vacuum can be applied via the connector156 to irrigate and/or aspirate the region of the body within which theprobe assembly 110 is disposed. Similarly stated, this arrangementresults in the connector 156 being placed in fluid communication withthe lumen 122 defined by the transmission member 120.

The distal end portion 153 of the housing 151 is configured to receivethe transducer horn 163 such that the transducer horn 163 is coupled toan inner surface of the housing 151. More specifically, the transducerhorn 163 can be disposed at least partially within the housing 151 suchthat the transducer horn 163 can be moved relative to the housing 151(e.g., when amplifying the ultrasonic energy), but not moved out of thehousing 151 during normal use. The transducer horn 163 includes aproximal end portion 164 and a distal end portion 165 and defines alumen 166 therethrough. The lumen 166 is configured to receive a portionof the bolt 158 at the proximal end portion 164 of the transducer horn163 and a portion of the probe assembly 120 at the distal end portion165 of the transducer horn 163, both of which are described in furtherdetail herein.

As shown in FIG. 2, the back plate 160, the insulators 161, and thepiezoelectric rings 162 are disposed within the housing 151 and aboutthe bolt 158. More specifically, the arrangement of the back plate 160,the insulators 161, and the piezoelectric rings 162 is such that theback plate 160 is disposed proximal to the insulators 161 and thepiezoelectric rings 162. The piezoelectric rings 162 are each disposedbetween the insulators 161. Similarly stated, a first insulator 161 isdisposed proximal to the piezoelectric rings 162 and a second insulator161 is disposed distal to the piezoelectric rings 162. The piezoelectricrings 162 are in electric communication (e.g., via wires not shown inFIGS. 1 and 2) with the ultrasonic generator 180, as described infurther detail herein.

As shown in FIG. 2, a portion of the bolt 158 is configured to bedisposed within the lumen 166 defined by the transducer horn 163. Morespecifically, the portion of the bolt 158 forms a threaded fit with aninner surface of the transducer horn 163 that defines the lumen 166. Inthis manner, the bolt 158 can be advanced within the lumen 166 such thatthe bolt 158 exerts a compressive force on the backing plate 160, theinsulators 161, and the piezoelectric rings 162. Thus, the backing plate160, the insulators 161, and the piezoelectric rings 162 are retainedbetween a head of the bolt 158 (e.g., at the proximal end) and aproximal surface of the transducer horn 163. The torque applied to thebolt and/or the clamping force exerted between the head of the bolt 158and the proximal surface of the transducer horn 163 is such that thatthe deviation of the transducer natural frequency deviation is withinten percent from nominal. Therefore, in use, the piezoelectric rings 162can vibrate and/or move the transducer horn 163, as further describedherein.

The bolt 158 further defines a lumen 159 such that a proximal endportion of the bolt 158 can receive a distal end portion of the flowtube 157. In this manner, the lumen 159 defined by the bolt 158 and theflow tube 157 collectively place the lumen 166 defined by the transducerhorn 163 in fluid communication with the connector 156. Thus, the lumen166 of the transducer horn 163 can be placed in fluid communication witha volume substantially outside of the proximal end of the housing 151.

As shown in FIGS. 1 and 2, the probe assembly 110 includes at least atransmission member 120 and a coupler 130. The coupler 130 includes aproximal end portion 131 and a distal end portion 132 and defines alumen 133 that extends therethrough. The proximal end portion 131 of thecoupler 130 is disposed within the lumen 166 at the distal end portion165 of the transducer horn 163 and forms a threaded fit with the innersurface of the transducer horn 163 that defines the lumen 166. Thedistal end portion 131 of the coupler 130 is configured to receive aportion of the transmission member 120 to fixedly couple thetransmission member 120 to the coupler 130. In this manner, the probeassembly 110 can be removably coupled to the transducer assembly 150 viathe coupler.

The transmission member 120 is an elongate tube having a proximal endportion 121 and a distal end portion 122. The transmission member 120can be any suitable shape, size, or configuration and is described infurther detail herein with respect to specific embodiments. In someembodiments, the transmission member 120 can optionally include anysuitable feature configured to increase the flexibility (e.g., decreasethe stiffness) of at least a portion of the transmission member 120,thereby facilitating the passage of the transmission member 120 througha tortuous lumen within a patient (e.g., a urinary tract, a vein,artery, etc.). For example, in some embodiments, a portion of thetransmission member 120 can be formed from a material of lower stiffnessthan a different portion of the transmission member 120 formed from amaterial of greater stiffness. In some embodiments, the stiffness of atleast a portion of the transmission member 120 can be reduced bydefining an opening (e.g., notch, a groove, a channel, a cutout, or thelike), thereby reducing the area moment of inertia of the portion of thetransmission member 120, as described herein with respect to specificembodiments.

In use, a user (e.g., a surgeon, a technician, physician, etc.) canoperate the ultrasonic system 100 to deliver ultrasonic energy to atarget bodily tissue within a patient. The user can, for example, engagethe pedals 172 of the foot switch 170 such that the ultrasonic generator180 generates an alternating current (AC) and voltage with a desiredultrasonic frequency (e.g., 20,000 Hz). In this manner, the ultrasonicgenerator 180 can supply AC electric power to the piezoelectric rings162. The AC electric power can urge the piezoelectric rings 162 tooscillate (e.g., expand, contract, or otherwise deform) at the desiredfrequency, which, in turn, causes the transducer horn 163 to moverelative to the housing 151. Thus, with the probe assembly 110 coupledto the transducer horn 163, the movement of the transducer horn 163vibrates and/or moves the probe assembly 110. In this manner, the distalend portion 122 of the transmission member 120 can be disposed with aportion of the patient adjacent to a target tissue such that thetransmission member 120 transfers at least a portion of the ultrasonicenergy to the target tissue (not shown in FIGS. 1 and 2). For example,in some embodiments, a distal tip of the transmission member 120 canimpact a target tissue such as, for example, to break apart theocclusion. In some embodiments, the movement of the distal end portion122 of the transmission member 120 is such that cavitations occur withinthe portion of the patient. In this manner, the cavitations can furtherbreak apart a target tissue. In some embodiments, the ultrasonic system100 can optionally be used to aspirate and/or to supply irrigation to atarget tissue site.

While described above in a general way, an ultrasonic energy system,such as the ultrasonic energy system 100, can include any suitable probeor transmission member of the types shown herein having increasedflexibility to facilitate the passage of the transmission member througha tortuous lumen within a patient. For example, in some embodiments, atransmission member can have a suitable flexibility such that at least aportion of the transmission member can elastically (e.g., notpermanently) deform within the tortuous anatomical structure. Forexample, FIG. 3 is a schematic illustration of a transmission member220, according to an embodiment. The transmission member 220 can beincluded in any suitable ultrasonic energy system shown and describedherein, such as, for example, the system 100 described above withreference to FIGS. 1 and 2. The transmission member 220 is amonolithically-constructed elongate member including a side wall 221 anddefining a lumen 222 along a longitudinal axis A₁. In this manner, thetransmission member 220 can provide aspiration from and/or irrigation(via the lumen 222, and the connecting lumens of any component to whichthe transmission member 220 is coupled) to a target tissue site duringan ultrasonic procedure.

As shown in FIG. 3, the transmission member 220 includes a first portion223, a second portion 224, and a third portion 225. The first portion223 can be, for example, a proximal end portion, and can be at leastoperably coupled to an ultrasonic energy source 280, such as forexample, the ultrasonic generator 180 and/or the transducer assembly 150described above. For example, in some embodiments, the first portion 223can be disposed within a lumen of a coupler member (not shown), asdescribed above with reference to FIG. 2. In such embodiments, thecoupler member can be coupled to the ultrasonic energy source 280, thus,operably coupling the transmission member 220 to the ultrasonic energysource 280. The second portion 224 can be, for example, a distal endportion of the transmission member 220, and can be disposed within abody (not shown) to transfer ultrasonic energy from the first portion223 into a bodily tissue.

The third portion 225 is disposed between the first portion 223 and thesecond portion 224. The third portion 225 defines a cross-sectional areamoment of inertia that is less than a cross-sectional area moment ofinertia of the first portion 223 and/or the second portion 224. In thismanner, the transmission member 220 has a suitable flexural stiffness tobe disposed along and/or within a tortuous path within the body suchthat the transmission member 220 efficiently and reliably transmitsultrasonic energy from the first portion 223 to the second portion 224.More particularly, the lower area moment of inertia of third portion 225allows the third portion 225 to elastically deform more easily than thefirst portion 223 and/or the second portion 224. Said another way, thethird portion 225 can bend (e.g., elastically) more easily about an axisthat is perpendicular to the longitudinal axis A₁ of the transmissionmember 220 than can the first portion 223 and/or the second portion 224.

Moreover, the greater flexural stiffness of the first portion 223 and/orthe second portion 224 can reduce losses of ultrasonic energytransmitted through the transmission member 220 that are associated withmore flexible materials and/or members. Similarly stated, the spatialvariation in the area moment of inertia results higher transmissionefficiency than would otherwise be obtained when forming thetransmission member 220 to have a constant, lower flexural stiffness.Because the transmission member 220 is monolithically constructed, it isdevoid of material interfaces that are known to cause reflection of theultrasonic energy waves (and thereby inefficient transfer of the same).Additionally, because the transmission member 220 is monolithicallyconstructed, there is a reduced likelihood that the transmission member220 will fail during use as a result of discontinuities and/or stressconcentration risers associated with the joining of separatelyconstructed pieces.

The transmission member 220 can be formed from any suitable materialsuch as, for example, Type 304 stainless steel, Type 316 stainlesssteel, nickel titanium alloy (nitinol), or any other super elastic metalor metal alloy. In some embodiments, the first portion 223, the secondportion 224, and/or the third portion 225 can be formed from a materialthat is dissimilar from the material of the other portions. For example,in some embodiments, the first portion 223 and the second portion 224can be formed from a first material and the third portion 225 can beformed from a second material. In such embodiments, the first materialcan have a modulus of elasticity that is substantially greater than themodulus of elasticity of the second material. For example, in someembodiments, the first portion 223 and the second portion 224 can beformed from Type 304 stainless steel and the third portion 225 can beformed from nitinol. In this manner, the first portion 223 and thesecond portion 224 can have a higher rigidity than that of the thirdportion 225. Similarly stated, the third portion 225 can have a lowerflexural stiffness (defined above) than the flexural stiffness of thefirst portion 223 and the second portion 224.

In other embodiments, the monolithically-formed transmission member 220can be formed from a substantially uniform material (e.g., a singlematerial). Similarly stated, in some embodiments, the flexural stiffnessof the first portion 223 and the second portion 224 can be greater thanthe flexural stiffness of the third portion 225 while being formed fromthe same material. In such embodiments, the spatial variation in thearea moment of inertia is achieved by varying the cross-sectional sizeand/or shape of the transmission member 220 along its longitudinal axisA₁. For example, in some embodiments, the transmission member 220 can besubstantially cylindrical and can have a uniform outer diameter along alength of the transmission member 220. Similarly stated, the firstportion 223, the second portion 224, and the third portion 225 can eachhave substantially the same outer diameters. In such embodiments, thefirst portion 223, the second portion 224, and the third portion 225 canhave a dissimilar inner diameter. For example, the first portion 223and/or the second portion 224 can have an inner diameter that is smaller(resulting in a thicker sidewall 221) than the inner diameter of thethird portion 225. Thus, the first portion 223 and/or the second portion224 have an area moment of inertia that is greater than the area momentof inertia of the third portion 225. In this manner, the first portion223 and/or the second portion 224 have a flexural stiffness that isgreater than the flexural stiffness of the third portion 225.

In other embodiments, the outer diameter of the first portion 223 and/orthe outer diameter of the second portion 224 can be greater than theouter diameter of the third portion 225. Thus, by maintaining a similarinner diameter, the first portion 223 and/or the second portion 224 canhave a greater area moment of inertia than the area moment of inertia ofthe third portion 225. In this manner, the first portion 223 and/or thesecond portion 224 have a flexural stiffness greater than the flexuralstiffness of the third portion 225.

In yet other embodiments, the nominal outer diameter and the nominalinner diameter of the transmission member can be substantially constant.In such embodiments, a portion of a transmission member can includeand/or define a discontinuity or change in cross-sectional shapeconfigured to reduce the area moment of inertia of at least the portionof the transmission member. For example, FIGS. 4-6 are schematicillustrations of a transmission member 320, according to an embodiment.The transmission member 320 can be included in any suitable ultrasonicenergy system such as, for example, the system 100 described above withreference to FIGS. 1 and 2. The transmission member 320 is amonolithically-constructed elongate member including a side wall 321 anddefining a lumen 322 along a longitudinal axis A₂. In this manner, thetransmission member 320 can provide aspiration from and/or irrigation(via the lumen 322) to a target tissue site during an ultrasonicprocedure.

The transmission member 320 includes a first portion 323 and a secondportion 324. The first portion 323 can be, for example, a proximal endportion and can be at least operably coupled to an ultrasonic energysource 380, such as for example, the ultrasonic generator 180 and/or thetransducer assembly 150 described above. For example, in someembodiments, the first portion 323 can be disposed within a lumen of acoupler member (not shown), as described above with reference to FIG. 2.In such embodiments, the coupler member can be coupled to the ultrasonicenergy source 380, thus, operably coupling the transmission member 220to the ultrasonic energy source 380. The second portion 324 can be, forexample, a distal end portion of the transmission member 320, and can bedisposed within a body (not shown) to transfer ultrasonic energy fromthe first portion 223 into a bodily tissue.

The transmission member 320 can be substantially cylindrical and canhave a uniform outer diameter d_(o) along a length L_(t) of thetransmission member 320. The walls 321 of the transmission member 321can be configured such that the transmission member 320 also has asubstantially uniform inner diameter d_(i). Similarly stated, the firstportion 323 and the second portion 324 can each have substantially thesame outer diameters and substantially the same inner diameters.

The transmission member 320 can be any suitable size. For example, insome embodiments, the walls 321 have a thickness t of approximately0.006 inches, the outer diameter d_(o) is approximately 0.032 inches,and the inner diameter d_(i) is approximately 0.020 inches. In otherembodiments, the outer diameter d_(o) of the transmission member 320 canbe between approximately 0.014 and 0.050 inches and the inner diameterd_(i) can be between approximately 0.010 and 0.040 inches. In someembodiments, the length L_(t) of the transmission member 320 isapproximately 57.5 inches.

The transmission member 320 further defines an elongate opening 326(e.g., a notch, a groove, a channel, a cutout, etc.) along at least aportion of the longitudinal axis A₂ that is in fluid communication withthe lumen 322. The opening 326 can be any suitable shape, size, orconfiguration. For example, as shown in FIG. 4, the opening 326 can besubstantially symmetrical relative to a plane perpendicular to thelongitudinal axis A₂. Moreover, the transmission member 320 can beconfigured such that the elongate opening 326 has a desired length L_(n)and a desired depth D_(n). For example, in some embodiments, the lengthL_(n) of the opening 326 can be approximately 5 times the outer diameterd_(o) of the transmission member. In other embodiments, the length L_(n)of the opening 326 can be greater than 5 times the outer diameter d_(o)of the transmission member. In still other embodiments, the length L_(n)of the opening 326 can be related to the length L_(t) of thetransmission member 320. For example, in some embodiments, the lengthL_(n) of the opening 326 can be between 40 percent and 90 percent of thelength L_(t) of the transmission member 320.

The depth D_(n) of the opening 326 can be, for example, at least half ofthe outer diameter d_(o) of the transmission member 320 (resulting in asubtended angle, as described below, of approximately 180 degrees). Inother embodiments, the depth D_(n) of the opening 326 can beapproximately 0.016 inches. In other embodiments, the depth D_(n) of theopening 326 can be between approximately 0.2 to 0.8 times the outerdiameter d_(o) of the transmission member 320.

As shown in FIGS. 5 and 6, the cross-sectional shape of the transmissionmember 320 is substantially changed at positions along the longitudinalaxis A₂. More specifically, FIG. 5 illustrates a cross-sectional shapeof the transmission member 320 taken at a location along thelongitudinal axis A₂ away from a region of the opening 326, and FIG. 6illustrates a substantially arced cross-sectional shape of thetransmission member 320 taken at a location along the longitudinal axisA₂ that includes the opening 326. As shown in FIG. 6, the presence ofthe opening 326 results in the transmission member 320 having anarc-shaped cross-sectional shape along a portion thereof. Thetransmission member 320 can be configured such that the arcedcross-sectional shape has a subtended angle α of between approximately20 degrees and approximately 120 degrees. In other embodiments, thetransmission member 320 is configured such that the arcedcross-sectional shape has a subtended angle α of up to approximately 180degrees.

The opening 326 can be such that the transmission member 320 has an areamoment of inertia at a position along the longitudinal axis A₂ havingthe arced cross-sectional shape that is substantially less than an areamoment of inertia at a position along the longitudinal axis A₂ havingthe annular cross-sectional shape. In this manner, the flexuralstiffness of the transmission member 320 at a position having the arcedcross-sectional shape is substantially less than the flexural stiffnessof the transmission member 320 at a position having the annularcross-sectional shape. Furthermore, because the walls 321 have asubstantially uniform thickness t, the flexibility of at least a portionof the transmission member 320 can be increased while substantiallylimiting the loss of stiffness in the axial direction.

The lower area moment of inertia of transmission member 320 at a portionof the transmission member 320 having the arced cross-sectional shapeallows the portion to elastically deform more than a portion of thetransmission member 320 having a greater area moment of inertia (e.g.,having the annular cross-sectional shape). More specifically, theportion having the arced cross-sectional shape can bend (e.g.,elastically) about an axis that is perpendicular to the longitudinalaxis A₂ of the transmission member 320 without kinking, breaking, orotherwise plastically deforming.

The lower flexural stiffness of the transmission member 320 can allow atleast the portion of the transmission member 320 having the arcedcross-sectional shape to elastically deform a desired amount while beingpassed through a tortuous anatomical structure (e.g., a urinary tract,vein or artery), thereby reducing patient discomfort. Moreover, theportions of the transmission member 320 with the arced cross-sectionalshape can retain a sufficient stiffness in the axial direction tosubstantially limit losses of ultrasonic energy transmitted through thetransmission member 320 that would otherwise be lost due to forming thetransmission member 320 from a material having a lower stiffness. Inaddition, the transmission member 320 can be configured such that theopening 326 is disposed at a suitable distance from a distal end of thetransmission member 320. Thus, the outer diameter d_(o) of thetransmission member 320 can be sufficiently large such that a distal tipof transmission member 320 can deliver ultrasonic energy to a targettissue.

Although not shown in FIGS. 4-6, in some embodiments, a transmissionmember can be at least partially disposed within an outer member of aprobe assembly. For example, in some embodiments, a probe assembly caninclude an outer member configured to substantially circumscribe thetransmission member. In such embodiments, the outer member can be, forexample, a catheter or sheath fixedly coupled to the transmission membervia an adhesive. In this manner, the outer member can be configured toretain the transmission member within a set of walls (e.g., within alumen defined by the set of walls) in the event of breakage, therebylimiting the risk of a portion of the transmission member being lostwithin a portion of the patient.

For example, FIGS. 7 and 8 are schematic illustrations of a probeassembly 410, according to an embodiment. The probe assembly 410includes a transmission member 420 and an outer member 440. The probeassembly 410 can be included in any suitable ultrasonic energy systemsuch as, for example, the system 100 described above with reference toFIGS. 1 and 2. The transmission member 420 includes a side wall 421 anddefines a lumen 422 along a longitudinal axis A₃. In this manner, thetransmission member 420 can provide aspiration from and/or irrigation(via the lumen 422) to a target tissue site during an ultrasonicprocedure, as further described below.

The transmission member 420 includes a first portion 423 and a secondportion 424. The first portion 423 can be, for example, a proximal endportion, and can be at least operably coupled to an ultrasonic energysource 480, such as for example, the ultrasonic generator 180 and/or thetransducer assembly 150 described above. For example, in someembodiments, the first portion 423 can be disposed within a lumen of acoupler member (not shown), as described above with reference to FIG. 2.In such embodiments, the coupler member can be coupled to the ultrasonicenergy source 480, thus, operably coupling the transmission member 420to the ultrasonic energy source 480. The second portion 424 can be, forexample, a distal end portion of the transmission member 420, and can bedisposed within a body (not shown) to transfer ultrasonic energy fromthe first end portion 423 into a bodily tissue.

The transmission member 420 defines an elongate opening 426 (e.g., anotch, a groove, a channel, a cutout, etc.) along at least a portion ofthe longitudinal axis A₃ that is in fluid communication with the lumen422. The opening 426 can be any suitable shape, size, or configuration.The transmission member 420 can be substantially similar to thetransmission member 320 described above with reference to FIGS. 4-6.Therefore, the transmission member 420 is not described in furtherdetail herein.

The outer member 440 includes a proximal end portion 441 and a distalend portion 442 and defines a lumen 443 therethrough. The proximal endportion 441 can be configured to be disposed adjacent a coupler member.The distal end portion 442 can be disposed adjacent a distal tip of thetransmission member 420. More specifically, the distal end portion 442can be disposed a desired distance from the distal tip of thetransmission member 420 such that the outer member 440 does notsubstantially dampen and/or otherwise interfere with the vibrationand/or movement of the distal tip of the transmission member 420 and/orthe transmission of the ultrasonic energy therethrough. In someembodiments, the outer member 440 is disposed from the distal end tip byapproximately 0.050 to 0.150 inches.

The outer member 440 is coupled to the transmission member 420 such thata portion of the outer member 440 is disposed about the elongate opening426. In this manner, the lumen 422 is maintained in fluid isolation froma region outside of the transmission member 420. Thus, the lumen 422 canbe used to aspirate and/or irrigate a target tissue site disposedadjacent the distal tip of the transmission member 420 during anultrasonic procedure. More specifically, the ultrasonic energy source480 can supply ultrasonic energy through the transmission member 420 toa target tissue and the ultrasonic energy source 480 (or other device)can be configured to simultaneously aspirate and/or irrigate the targettissue site via the lumen 422. In addition to maintaining fluidisolation of the lumen 422, the outer member 440 also circumscribes thetransmission member 420 to maintain any portions thereof that may resultin the event of a failure. Similarly stated, in some embodiments, theouter member 440 can be fixedly coupled to the transmission member 420such that if a portion of the transmission member 420 breaks, it will beretained within the outer member 440.

In some embodiments, the outer member 440 is fixedly coupled to thetransmission member 420. For example, in some embodiments, the outermember 440 can be fixedly coupled to the transmission member 420 via anadhesive, a friction fit, a threaded coupling, or any other suitablecoupling method. The outer member 440 can be any suitable memberconfigured to substantially circumscribe the transmission member 420.For example, in some embodiments, the outer member 440 can be acatheter. In other embodiments, the outer member 440 can be formed frommultiple layers of material having any given properties. For example, insome embodiments, the outer member 440 can be formed with an outer layerthat can be polytetrafluoroethylene (PTFE). In other embodiments, theouter layer can include a hydrophobic coating or a hydrophilic coating.In some embodiments, the outer member 440 can include an inner layerconfigured to enhance the adhesion properties of the outer member 440 tofacilitate the coupling of the outer member 440 to the transmissionmember 420. Moreover, the arrangement of the outer member 440 is suchthat the outer member 440 does not limit the desired flexibility of thetransmission member 420 disposed therein. Similarly stated, the outermember 420 can be sufficiently flexible to allow the transmission member420 to deflect within a bodily lumen, as described above.

While the transmission member 420 is shown in FIG. 7 as having anopening that is substantially symmetrical about a plane perpendicular tothe longitudinal axis A₃, in some embodiments, a transmission member caninclude an opening that is substantially asymmetrical. For example, FIG.9 is an illustration of a probe assembly 510, according to anembodiment. The probe assembly 510 includes a transmission member 520,defining an elongate opening 526, and an outer member 540. Thetransmission member 520 and the outer member 540 can be substantiallysimilar in form and function to the transmission member 420 and theouter member 440, respectively, described with reference to FIGS. 7 and8. Thus, the transmission member 520 and the outer member 540 are notdescribed in further detail herein. The transmission member 520 differsfrom the transmission member 420, however, in the arrangement of theopening 526. As shown in FIG. 9, the opening 526 is configured to besubstantially asymmetric about a plane parallel to a longitudinal axisA₄ of the transmission member 520. In this manner, the flexuralstiffness of the transmission member 520 can be further varied along alength of the opening 526 according to the cross-sectional shape of thetransmission member 520 at a given position. More specifically, bydefining an asymmetrical opening 526, the cross-sectional shape of thetransmission member 520 can be selectively varied along the length ofthe opening 526. Furthermore, because the area moment of inertia isdependent on the cross-sectional shape, the area moment of inertia isalso selectively varied along the length of the opening 526.

While the probe assembly 510 is shown in FIG. 9 as having a transmissionmember 520 defining a single opening 526, in some embodiments, atransmission member can include any number of openings. For example,FIG. 10 is an illustration of a probe assembly 610, according to anembodiment. The probe assembly 610 includes a transmission member 620,defining a first opening 626 and a second opening 628, and an outermember 640. Portions of the transmission member 620 and the outer member640 can be substantially similar in form and function to portions of thetransmission member 520 and the outer member 540, respectively,described above with reference to FIG. 9. Thus, the portions oftransmission member 620 and the outer member 640 are not described infurther detail herein.

The transmission member 620 differs from the transmission member 420 andthe transmission member 520, however, by including the first opening 626and the second opening 628. In some embodiments, the first opening 626and the second opening 628 can be substantially similar in shape, size,and/or configuration. In other embodiments, the first opening 626 canbe, for example, symmetric about a plane perpendicular to a longitudinalaxis A₅ of the transmission member 620 while the second opening 628 canbe, for example, asymmetric about a plane perpendicular to thelongitudinal axis A₅ (or vice versa). The first opening 626 can bearranged at any spatial orientation relative to the second opening 628.For example, while shown in FIG. 10 and being disposed on opposite sidesof the transmission member 620, in some embodiments, the first opening626 and the second opening 628 can be disposed adjacent each other on asimilar side of the transmission member 620. In this manner, the firstopening 626 and the second opening 628 can be selectively configured tomodify the flexural stiffness of the transmission member 620. Moreover,the arrangement of the first opening 626 and the second opening 628 canbe such that the first opening 626 and the second opening 628 cansubstantially reduce the likelihood of the transmission member 620kinking during bending.

Referring now to FIG. 11, a flowchart illustrates a method 790 fortransferring ultrasonic energy to a target tissue within a body of apatient, according to an embodiment. In some embodiments, the method 790includes inserting at least a distal end portion of amonolithically-constructed transmission member into a bodily lumen, at791. In some embodiments, the transmission member can include a flexibleportion disposed between a proximal end portion and a distal end portionthat has an area moment of inertia less than an area moment of inertiaof the proximal end portion and/or an area moment of inertia of thedistal end portion. For example, in some embodiments, the transmissionmember can be substantially similar to any of the transmission membersdescribed above (e.g., the transmission member 320 described above withreference to FIGS. 4-6). In this manner, the transmission member caninclude an opening (e.g., similar to the transmission member 320) ormultiple openings (e.g., similar to the transmission member 620)disposed along the transmission member such that the cross-sectionalshape of the transmission member is changed (e.g., a cross-sectionalarea of the transmission member is reduced at a position along theopening), thereby decreasing a flexural stiffness of the transmissionmember. Moreover, in some embodiments, at least a portion of thetransmission member can be disposed within an outer member configured tosubstantially circumscribe at least a portion of the transmission member(e.g., as described above with reference to FIGS. 7 and 8).

The method 790 includes transmitting ultrasonic energy from the proximalend portion of the transmission member to the distal end portion of thetransmission member, at 792. For example, in some embodiments, theproximal end portion of the transmission member can be operably coupledto an ultrasonic energy source such that the ultrasonic energy sourcesupplies the ultrasonic energy to the transmission member. Moreover, thedistal end portion (e.g., at least a distal tip) of the transmissionmember can be disposed adjacent a target tissue within the body of thepatient. In this manner, the transmission member can transmit at least aportion of the ultrasonic energy to the target tissue.

In some embodiments, the method 790 can optionally include aspirating atleast a portion of the target tissue via a lumen defined by thetransmission member, at 793. For example, in some embodiments, thetransmission member can define a lumen configured to extend through theproximal end portion and the distal end portion of the transmissionmember. Furthermore, in embodiments in which the transmission memberdefines an elongate opening, the outer member disposed about thetransmission member can be configured to fluidically isolate the lumenfrom a volume outside of the outer member. Thus, a negative pressure canbe applied to the proximal end portion of the transmission member suchthat a portion of the target tissue (e.g., a portion of the targettissue that is broken apart by ultrasonic energy) can be aspiratedthrough the lumen defined by the transmission member.

The embodiments and/or components described herein can be packagedindependently or any portion of the embodiments can be packaged togetheras a kit. For example, in some embodiments, a kit can include anultrasonic transducer assembly (e.g., such as the ultrasonic transducerassembly 150 described above with reference to FIG. 2) and any suitablenumber of transmission members (e.g., such as the various embodimentsdescribed above with reference to FIGS. 3-11). The transmission membersincluded in the kit can each define a given flexural stiffness that canbe different from the flexural stiffness of the other transmissionmembers included in the kit. For example, in some embodiments, each ofthe transmission members included in the kit can be substantiallysimilar in size and shape as the other transmission members included inthe kit but each transmission member can each define a flexuralstiffness that is substantially unique to the specific transmissionmember. Expanding further, in some embodiments, at least onetransmission member in the kit can include an opening along a length ofthe transmission member that substantially reduces an area moment ofinertia of the transmission member along the length of the opening. Inthis manner, one or more transmission members can define an opening ofunique shape, size, or configuration such that each transmission memberdefines a unique flexural stiffness.

In some embodiments, a kit can include an ultrasonic generator similarto the ultrasonic generator 180 shown and described above. Theultrasonic generator can be configured to distinguish each transmissionmember contained within the kit, and can automatically adjust theelectronic signal produced and/or conveyed to the ultrasonic transducerassembly to correspond to the transmission member coupled thereto. Forexample, because transmission members defining different levels offlexural stiffness may also have different natural (or resonant)frequencies, in such embodiments, the ultrasonic generator can adjustthe frequency of the electronic signal produced to correspond to thenatural frequency of the transmission member that is coupled to theultrasonic transducer assembly.

The processor included in any of the ultrasonic generators can be ageneral-purpose processor (e.g., a central processing unit (CPU)) orother processor configured to execute one or more instructions stored inthe memory. In some embodiments, the processor can alternatively be anapplication-specific integrated circuit (ASIC) or a field programmablegate array (FPGA). The processor can be configured to execute specificmodules and/or sub-modules that can be, for example, hardware modules,software modules stored in the memory and executed in the processor,and/or any combination thereof. The memory included in the ultrasonicgenerator 180 can be, for example, flash memory, one time programmablememory, a random access memory (RAM), a memory buffer, a hard drive, aread-only memory (ROM), an erasable programmable read-only memory(EPROM), and/or so forth. In some embodiments, the memory includes a setof instructions to cause the processor to execute modules, processesand/or functions used to generate, control, amplify, and/or transferelectric current to another portion of the system, for example, thetransducer assembly 150.

Some embodiments described herein, such as, for example, embodimentsrelated to the ultrasonic generators described above, relate to acomputer storage product with a non-transitory computer-readable medium(also can be referred to as a non-transitory processor-readable medium)having instructions or computer code thereon for performing variouscomputer-implemented operations. The computer-readable medium (orprocessor-readable medium) is non-transitory in the sense that it doesnot include transitory propagating signals per se (e.g., a propagatingelectromagnetic wave carrying information on a transmission medium suchas space or a cable). The media and computer code (also can be referredto as code) may be those designed and constructed for the specificpurpose or purposes. Examples of non-transitory computer-readable mediainclude, but are not limited to: magnetic storage media such as harddisks, floppy disks, and magnetic tape; optical storage media such asCompact Disc/Digital Video Discs (CD/DVDs), Compact Disc-Read OnlyMemories (CD-ROMs), and holographic devices; magneto-optical storagemedia such as optical disks; carrier wave signal processing modules; andhardware devices that are specially configured to store and executeprogram code, such as Application-Specific Integrated Circuits (ASICs),Programmable Logic Devices (PLDs), Read-Only Memory (ROM) andRandom-Access Memory (RAM) devices. Other embodiments described hereinrelate to a computer program product, which can include, for example,the instructions and/or computer code discussed herein.

Examples of computer code include, but are not limited to, micro-code ormicro-instructions, machine instructions, such as produced by acompiler, code used to produce a web service, and files containinghigher-level instructions that are executed by a computer using aninterpreter. For example, embodiments may be implemented using Java,C++, or other programming languages (e.g., object-oriented programminglanguages) and development tools. Additional examples of computer codeinclude, but are not limited to, control signals, encrypted code, andcompressed code.

The ultrasonic transmission members described herein can be fabricatedand/or produced using any suitable methods. In some embodiments atransmission member can be formed via one of more manufacturing process.For example, in some embodiments, a transmission member can be formedvia a tube drawing (e.g., drawn through a progressively smaller die (anextrusion process). In embodiments wherein the transmission memberdefines an elongate opening (e.g., the transmission member 320 describedabove), the opening can be formed via water jet cutting, laser cutting,machining (e.g., milling, turning, shearing, etc.). Expanding further,in some embodiments it can be desirable to form an opening along alength of a transmission member via a water jet process because suchprocesses do not produce a heat-affected zone. Thus, the elastic modulusof the material (e.g., stainless steel or the like) that forms thetransmission member is not changed. Conversely, in some embodiments itcan be desirable to form an opening along a length of a transmissionmember via a laser cutting process because such processes produce aheat-affected zone. In such embodiments, the heating of theheat-affected zone of the transmission member due to the laser cuttingof the opening can have a similar affect as tempering, thus, thestiffness of the material in a region within the heat-affected zone(e.g., along or adjacent to the opening) can be reduced.

Although certain transmission members (e.g., transmission member 320)are described above as being monolithically constructed, in otherembodiments, any of the transmission members described herein can beconstructed from two or more separately constructed components that arelater joined together.

While the flexural stiffness of transmission members described above isspatially varied by altering the size or shape of the transmissionmember, in alternate embodiments, manufacturing techniques can be usedto spatially vary of the flexural stiffness a transmission member whilemaintaining a uniform cross-sectional shape. For example, in someembodiments, a portion of a transmission member (e.g., the third portion222 of the transmission member 220) can be heat-treated such that theelastic modulus of the portion of the transmission member is changedrelative to the elastic modulus of a portion not heat treated. Forexample, in some embodiments, a portion of a transmission member can betempered. In other embodiments, a transmission member in its entiretycan be variably heat treated. For example, in some embodiments, a firstportion can be tempered at a first temperature and a second portion canbe tempered at a second temperature, different form the first. In thismanner, the flexibility of the first portion and the flexibility of thesecond portion can be varied according to the temperature of tempering.

The proximal end portion of any of the transmission members describedherein can be coupled to the coupler member (e.g., the coupler member130) using any suitable mechanism. For example, as shown in FIG. 12, aprobe assembly 810 can include at least a transmission member 820 and acoupler 830. The transmission member 820 and the coupler 830 can besubstantially similar to the transmission member 120 and the coupler 130described above with reference to FIGS. 1 and 2, thus, some portions ofthe transmission member 820 and the coupler 830 are not described infurther detail herein. As shown, the coupler 830 includes a proximal endportion 831 and a distal end portion 832 and defines a lumen 833therethrough. The proximal end portion 831 is configured to form athreaded coupling with a transducer horn 863, as described above indetail with reference to FIG. 2. The lumen 833 has a diameter d₁ thatcan be any suitable size. In this manner, the coupler 830 can beconfigured to receive (within the lumen 833) a portion of thetransmission member 820, as described in further detail herein.

The transmission member 820 includes a proximal end portion 821 and adistal end portion (not shown in FIG. 12) and defines a lumen 822therethrough. The transmission member 820 can be any suitable shape,size, or configuration. For example, in some embodiments, at least aportion of the transmission member 820 is substantially annular andincludes an outer diameter d_(o) and an inner diameter d_(i). In someembodiments, the size and shape of the transmission member 820 (e.g.,the outer diameter d_(o)) can substantially correspond to the size andshape (e.g., the diameter d_(i)) of the lumen 833 defined by the coupler830 such that the proximal end portion 821 of the transmission member820 can be disposed therein.

For example, in some embodiments, the diameter d₁ of the lumen 833 canbe greater than the outer diameter d_(o) of the transmission member 830,thus, the transmission member 820 can be disposed within the lumen 833of the coupler 830. Furthermore, with the diameter d₁ of the lumen 833greater than the outer diameter d_(o) of the transmission member 820 anadhesive can be disposed within a void between the transmission member820 and the inner surface of the coupler 830. Thus, the transmissionmember 820 can be fixedly coupled to the coupler 830 without the needfor crimping, applying a compressive force to the transmission member orthe like. Expanding further, the transmission member 820 can be fixedlycoupled to the coupler 830 without plastically (e.g., permanently)deforming the transmission member, thereby decreasing the likelihood offailure and also decreasing losses due to reflections of ultrasonicenergy produced by discontinuity. In other embodiments, the transmissionmember 120 can be coupled via welding or brazing while still realizingthe benefits described above.

The transmission members described herein can be any suitable size. Forexample, in some embodiments, a transmission member (e.g., thetransmission member 820) can have an outer diameter d_(o) that isapproximately 0.032 inches and an inner diameter d_(i) that isapproximately 0.020 inches. In this manner, the transmission member 820can have a wall thickness of approximately 0.006 inches. In otherembodiments, the outer diameter d_(o) of the transmission member 820 canbe between approximately 0.014 to 0.050 inches and the inner diameterd_(i) can be between approximately 0.010 to 0.040 inches.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Where methods and/or schematics described above indicatecertain events and/or flow patterns occurring in certain order, theordering of certain events and/or flow patterns may be modified.Additionally certain events may be performed concurrently in parallelprocesses when possible, as well as performed sequentially. While theembodiments have been particularly shown and described, it will beunderstood that various changes in form and details may be made.

For example, although the transmission member 320 is shown and describedas defining an elongate opening that is substantially linear along thelongitudinal axis A₂, in other embodiments, a transmission member candefine an elongate opening that is helical and/or spiraled about thelongitudinal axis. In this manner, the area moment of inertia of theregion of the transmission member that defines the elongated opening canbe more uniform about the longitudinal axis.

Although the transducer assembly 150 is shown in FIG. 2 as including twoinsulators 161 and two piezoelectric rings 162, in other embodiments, atransducer assembly can include any suitable number of insulators 161and/or piezoelectric rings 162 in any suitable arrangement. Moreover,the insulators 161 can be formed from any suitable insulating material,ceramic materials (e.g., polyamide, expanded polytetraflouroethylene(EPTFE), or the like). Similarly, the piezoelectric rings 162 can be anysuitable piezoelectric material (e.g., lead zirkonate titanate (PZT-5),PZT-8, lead titanate (PT), lead metaniobate (PbNbO₆),polyvinylidenefluoride (PVDF), or the like).

Although various embodiments have been described as having particularfeatures and/or combinations of components, other embodiments arepossible having a combination of any features and/or components from anyof embodiments where appropriate. For example, in some embodiments, atransmission member can be a monolithically-constructed member asdescribed with respect to the transmission member 320, and can alsoinclude an outer member coupled thereto, as described above with respectto the transmission member 420.

What is claimed is:
 1. An apparatus, comprising: amonolithically-constructed transmission member defining a lumen along alongitudinal axis of the transmission member, the transmission memberincluding a first portion, a second portion, and a third portion, thefirst portion configured to be coupled to an ultrasonic energy source,the second portion including a distal tip configured to be disposedwithin a body, the distal tip configured to move in response to anultrasonic energy produced by the ultrasonic energy source to transferthe ultrasonic energy from the first portion through the second portionand into a bodily tissue, the third portion disposed between the firstportion and the second portion, the second portion defining a distal endopening in fluid communication with the lumen, the first portion and thesecond portion having a constant outer diameter, the third portiondefining a cross-sectional area moment of inertia that is less than atleast one of a cross-sectional area moment of inertia of the firstportion or a cross-sectional area moment of inertia of the secondportion, a sidewall of the third portion of the transmission memberdefining an elongated opening therethrough in fluid communication withthe lumen, the elongated opening having a depth at least half as largeas an outer diameter of the first portion of the transmission member;and an outer member fixedly coupled to the transmission member about theelongated opening.
 2. The apparatus of claim 1, wherein: the outermember is fixedly coupled to the transmission member via an adhesivesuch that the lumen is fluidically isolated from a region outside of theouter member.
 3. The apparatus of claim 1, wherein a cross-sectionalshape of the third portion of the transmission member is different thanat least one of a cross-sectional shape of the first portion or across-sectional shape of the second portion.
 4. The apparatus of claim1, wherein a cross-sectional shape of the sidewall defining theelongated opening is an arc.
 5. The apparatus of claim 1, furthercomprising: a fitting coupled to the first portion of the transmissionmember, the fitting configured to couple the transmission member to theultrasonic energy source.
 6. The apparatus of claim 1, wherein a lengthof the elongated opening is greater than five times a diameter of thetransmission member.
 7. The apparatus of claim 1, wherein across-sectional shape of the sidewall defining the elongated opening isan arc having a subtended angle of between approximately 20 degrees andapproximately 120 degrees.
 8. An apparatus, comprising: amonolithically-constructed transmission member defining a lumen along alongitudinal axis of the transmission member, the transmission memberincluding a first portion, a second portion, and a third portion, thefirst portion configured to be coupled to an ultrasonic energy source,the second portion including a distal tip configured to be disposedwithin a body, the distal tip configured to move in response to anultrasonic energy produced by the ultrasonic energy source to transferthe ultrasonic energy from the first portion through the second portionand into a bodily tissue, the third portion disposed between the firstportion and the second portion, the first portion and the second portionhaving a constant outer diameter, the third portion defining across-sectional area moment of inertia that is less than at least one ofa cross-sectional area moment of inertia of the first portion or across-sectional area moment of inertia of the second portion, a sidewallof the third portion of the transmission member defining an elongatedopening therethrough in fluid communication with the lumen, theelongated opening having a depth at least half as large as an outerdiameter of the first portion of the transmission member, the sidewalldefining the elongated opening forming an arc having a subtended angleof between approximately 20 degrees and approximately 120 degrees, across-sectional shape of the first portion being the same as across-sectional shape of the second portion.
 9. The apparatus of claim8, wherein at least one of the first portion or the second portion hasan inner diameter that is smaller than an inner diameter of the thirdportion.
 10. The apparatus of claim 8, further comprising: an outermember fixedly coupled to the transmission member via an adhesive. 11.The apparatus of claim 10, wherein an outer diameter of the outer memberis constant from a proximal end portion of the outer member to a distalend portion of the outer member.
 12. The apparatus of claim 8, wherein alength of the elongated opening is greater than five times a diameter ofthe transmission member.
 13. The apparatus of claim 8, wherein theelongated opening is one of a plurality of elongated openings defined bythe sidewall.
 14. A method, comprising: inserting at least a distal endportion of a monolithically-constructed transmission member into abodily lumen, the transmission member defining a lumen along alongitudinal axis of the transmission member, the transmission memberincluding a proximal end portion and a flexible portion disposed betweenthe proximal end portion and the distal end portion, the proximal endportion and the distal end portion having a constant outer diameter, theflexible portion defining a cross-sectional area moment of inertia thatis less than at least one of a cross-sectional area moment of inertia ofthe proximal end portion or a cross-sectional area moment of inertia ofthe distal end portion, the distal end portion defining a distal endopening in fluid communication with the lumen defined by thetransmission member, a sidewall of the flexible portion of thetransmission member defining an elongated opening therethrough in fluidcommunication with the lumen defined by the transmission member, theelongated opening having a depth at least half as large as an outerdiameter of the proximal end portion of the transmission member, anouter member coupled to the transmission member about the elongatedopening to prevent fluid communication between the lumen and a regionoutside of the outer member via the elongated opening; transmitting anultrasonic energy from the proximal end portion through the flexibleportion and the distal end portion such that a portion of the ultrasonicenergy is delivered to a target tissue within the bodily lumen; andaspirating at least a portion of the target tissue via the distal endopening and the lumen defined by the transmission member.
 15. The methodof claim 14, wherein the outer member is fixedly coupled to thetransmission member via an adhesive.
 16. An apparatus, comprising: amonolithically-constructed transmission member defining a lumen along alongitudinal axis of the transmission member, the transmission memberincluding a first portion, a second portion, and a third portion, thefirst portion configured to be coupled to an ultrasonic energy source,the second portion configured to be disposed within a body to transferan ultrasonic energy from the first portion into a bodily tissue, thethird portion disposed between the first portion and the second portion,the second portion defining a distal end opening in fluid communicationwith the lumen, the first portion and the second portion having aconstant outer diameter, the third portion defining a cross-sectionalarea moment of inertia that is less than at least one of across-sectional area moment of inertia of the first portion or across-sectional area moment of inertia of the second portion, a sidewallof the third portion of the transmission member defining an elongatedopening therethrough in fluid communication with the lumen, theelongated opening having a depth at least half as large as an outerdiameter of the first portion of the transmission member, a length ofthe elongated opening being between 40 percent and 90 percent of alength of the transmission member.
 17. The apparatus of claim 16,further comprising: an outer member fixedly coupled to the transmissionmember.
 18. The apparatus of claim 16, further comprising: an outermember fixedly coupled to the transmission member via an adhesive, aportion of the outer member disposed about the elongated opening suchthat the lumen is fluidically isolated from a region outside of theouter member.
 19. The apparatus of claim 16, wherein a cross-sectionalshape of the sidewall defining the elongated opening is an arc.
 20. Theapparatus of claim 16, further comprising: a fitting coupled to thefirst portion of the transmission member, the fitting configured tocouple the transmission member to the ultrasonic energy source.